Liquid Metal Corrosion Studies for Fusion Reactor Applications: Facility Development and Basic Research

In the present research work, under different operating conditions, the corrosion behavior of the Indian RAFMS (IN RAFMS: 9Cr-1.4 W) and its surrogate material, modified 9Cr-1Mo steel (P91) in molten Pb–Li has been investigated using a number of specially developed test facilities offering isothermal and non-isothermal (under static and flowing) conditions. The diffusion of Fe across the Pb–Li boundary layer has been established to be the rate-controlling step in the case of IN RAFMS. Increase in temperature of exposure, flow velocity, and presence of a temperature gradient increases the attack of Pb–Li. Corrosion of ferritic/martensitic steels in Pb–Li is generally initiated by the dissolution of air-formed oxide layer which consisted of oxides of Fe and Cr. This accounts for an initial period of initial retarded corrosion rate which is termed as “Incubation period’ during which grain boundary penetration of Pb–Li was the dominating mode of corrosion. The mode of Pb–Li attack is changed with the dissolution of the oxide layer resulting in higher rates of corrosion.